Multiple radius pipe bending machine



Oct. 17, 1961 E. D. KEY

MULTIPLE RADIUS PIPE BENDING MACHINE 3 Sheets-Sheet 1 Filed March 18,1959 INVEN TOR. JZ/za4ri J K y.

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Oct. 17, 1961 KEY 3,004,582

MULTIPLE RADIUS PIPE BENDING MACHINE Filed March 18, 1959 :5Sheets-Sheet 2 IN VEN TOR.

E 5 Zia/47%)] A C 1961 E. D. KEY 3,00

MULTIPLE RADIUS PIPE BENDING MACHINE Filed March 18, 1959 3 Sheets-Sheet3 67 INVENTOR. A96? 17 ziwdr D, Key

Mich.

Filed Mar. 13, 1959, Ser. No. 800,256 4- Claims. (Cl. 153-38) Thisinvention relates to improvements in pipe bending machines and, moreparticularly, to improvements in bending machines suitable for coldbending pipe and conduit used for electric wiring installations. Thisapplication is a continuation-in-part of prior copending applicationSerial No. 733,377, filed May 6, 1958, for a Multiple Radius PipeBending Machine and now abandoned.

A primary object of this invention is to provide an extremely versatilepipe bending machine quickly and simply adaptable to accurately bendpipes of various diameters over a wide range of diiferent radii throughangles ranging from zero to slightly over 90 degrees.

Another object of this invention is to provide a pipe bending machinewhich may be preset so that each bending cycle is automaticallycontrolled providing precision bends that are smooth and consecutivelyidentical.

Still another object of this invention is to provide a pipe bendingmachine which enables the simultaneous bending of several pipes, therebysubstantially increasing efficiency and productive capacity.

A further object of this invention is to provide a pipe bending machinewhich enables the bent pipe to be easily extracted from the bendingshoes.

Still another object of this invention is to provide a pipe bendingmachine which can quickly and simply be disassembled and reassembled forcompact handling, thereby enhancing its portable characteristics andfacilirating its storage when not in use.

Other objects and advantages of this invention will become apparent tothose skilled in the art on reading the specification with reference tothe accompanying drawings, in which:

FIGURE 1 is a perspective view of the pipe bending machine embodying theinvention and illustrating the relationship of its component parts to apipe being bent;

FIGURE 2 is a perspective view of a small radius base ram and a seriesof ram extension dies for attachment thereto;

FIGURE 3 is a perspective view of a large radius base ram and a seriesof ram extension dies for attachment thereto;

FIGURE 4 is a vertical sectional view of a pipe bending shoe andadjacent ram extension dies as shown in FIGURE 1 and taken along line4-4 thereof;

FIGURE 5 is a vertical sectional view through a twocavity segmentedbending shoe connected to the outermost ram extension die andillustrating the relative positioning of the pipes in said cavities;

FIGURE 6 is a vertical sectional view through a fivecavity solid bendingshoe and illustrating the relative positioning of the pipes in saidcavities;

FIGURE 7 is a vertical sectional view of a five-cavity solid bendingshoe illustrating an alternate method for attaching said bending shoe tothe adjacent ram extension die;

FIGURE 8 is a fragmentary perspective view of FIG. 2 and illustratingthe operation of the holding shoe and holding shoe return mechanism asthey might appear when viewed from the position of arrow 8 near the leftend of FIG. 1;

FIGURE 9 is a perspective view of the power unit and a schematic view ofthe automatic control circuit;

.FIGURE 10 is a fragmentary vertical sectional view of the ram extensiondies and bending shoes supported by the roller carriage on the centraltrack bar;

FIGURE 11 is a fragmentary vertical sectional view of the rollercarriage shown in FIGURE 10 and taken along line 11-11 thereof;

FIGURE 12 is a fragmentary plan view of the bending machine illustratinga multiple bending operation;

FIGURE 13 is a vertical sectional view of the pipe end stop shown inFIGURE 12, taken along line 13-13 thereof and rotated clockwise;

FIGURE 14 is a view of an oifset bent pipe made with this machine;

FIGURE 15 is a view of a pipe bent into a figuration by this machine;and

FIGURE 16 is a view of a pipe bent in an angle of less than 90 degrees.

Referring now in detail to the drawings and as may be seen to bestadvantage in FIGURE 1, the automatic bending machine has beensub-divided for descriptive purposes into four basic operationalelements; a power unit 1, a bending ram assemblage 2, a pipe holdingfixture 3, and an automatic control mechanism for regulating thereciprocating travel of the bending ram assemblage. The relationship ofthe four operating elements as shown in FIGURE 1 enables the bendingmachine to be placed and operated on any comparatively flat surface ofsuitable size.

The power unit 1, as shown in FIGURES l and 9, comprises a conventionaldouble-acting hydraulic piston and saddle concylinder assembly, ahydraulic pump of suitable capacity and pressure, a fluid reservoir, andsuitable valves and passages to control the direction of piston andpiston rod travel. The particular power unit illustrated has an outerhousing 4 which is integral with the hydraulic cylinder and pumpassemblies. Power units developing thrust forces upwards of tons andacting through a horizontal travel distance of about fifty inches aresuitable for bending conduit sizes ordinarily encountered in electricwiring installations. The hydraulic pump is drivingly linked to electricmotor 5 by means of flexible belt 6 acting over motor pulley 7 and pumppulley 8 as shown in FIGURE 9. An electric servo motor 9 connected tothe shaft of lower control lever 10 enables rapid reversal of thedirection of the piston rod 12 and is energized by means of theautomatic control feature of this machine, which will be discussed indetail in a subsequent portion of this specification. Upper controllever 11 regulates the speed of travel of the hydraulically operatedpiston rod 12.

The bending ram assembly 2 is connected to the power unit 1 by means ofa female adapter in the rear body of the base ram 13 which slides overand is removably splined or keyed to the end of the piston rod 12 andlocked thereto by a set screw. The bending ram assembly 2 is comprisedof a base ram 13, a series of arcuate fillers or ram extension dies 14,and a plurality of pipe bending shoes 15 removably attached to thearcuate face of the outermost ram extension die. FIGURE 2 is aperspective view of a small radius base ram 13 and a series of ramextension dies 14 adaptable for separate and successive removableattachment to the forward face of the base ram 13. The arcuate faces ofthe base ram 13 and ram extension dies 14 are concentric and ascribecircular arcs of approximately 90 which extend about 45 to each side ofthe longitudinal center axis of the ram and hydraulic piston rod 12. Bythe addition of one or more of the ram extension dies 14 to the face ofthe base ram 13 the radius of the ram can be varied in incrementscorresponding to the thickness of each extension die. In this manner theradius of the smallbase ram 13 shown in FIGURE 2 can be increased to anydo- Pa jtented Oct. 17, 1961 3 sired radius by the successive attachmentof the required number of ram extension dies 14. However, an additionalbase ram of a radius approximately intermediate to the range or radiirequired is preferred for large radius bends because of its greaterrigidity in comparison to that of a small base ram equipped with a largenumber of ram extension dies. Accordingly, the large base ram 13 andextension dies 14 shown in FIGURE 3 have radii which sequentially followthe maximum extended radius of the small base ram shown in FIGURE 2. Theinnermost ramextension die is removably attached to the forward face ofthe base ram by means of two screws inserted at the back face of thebase ram through holes 16 which are in alignment with tapped holes inthe back side of the ram extension die. Successive attachment ofadditional ram extension dies to the innermost extension die is achievedby a pin and hinge type latching means, as shown in FIGURE 8. Hingeplates 17 are rigidly secured to each end of each ram extension die 14by screws 18, said hinge plates having collars 20 which when placed invertical alignment are removably secured together by the insertion ofpin 19. The upper and lower sides of the ram extension dies are providedwith grooves 21, as shown in FIGURE 4, having a vertical forward edgefor engaging the latching levers 22 on the pipe bending shoes 15. Thelatching levers 22 are held in engagement with grooves 21 by means ofspring clips 23, as may be best seen in FIGURE and are pivotally securedto the bending shoes by means of pivot pins 26. The pipe bending shoesare positioned along the arcuate forward face of the outermost ramextension die at spaced intervals as determined by the spacing ofpositioning holes 25 along the center of the face of the extension die14 and cooperate with pins 24 which protrude from the center of the rearsurface of the bending shoes 15. A sufficient number of pipe bendingshoes are used to provide ample surface area to adequately support thepipe as it is bent during the forward thrust of the bending ramassembly, assuring smooth, concentric bends. Distortion of the circularcross section of the pipe or conduit being bent is minimized by thesemi-circular cross section of the cavities in the face of the pipebending shoes which radially support the pipe or conduit aroundapproximately oneehalf its outer periphery.

The pipe bending shoes are either of a solid or segmented constructionhaving one or more die cavities in their forward working face. Asegmented. single-cavity bending shoe is shown in FIGURE 4; a segmenteddoublecavity bending shoe is shown in FIGURE 5; and a fivecavity solidbending shoe is illustrated in FIGURES 6 and 7. The unique segmentedconstructoin of the pipe bending shoes shown in FIGURES 4 and 5 isparticularly applicable to pipes having diameters in excess of one andone-half inches, although it may also be applied to bending shoes forsmaller diameter pipes. This segmented bending shoe feature enables theeasy extraction and release of bent pipes from the bending shoes with aminimum of effort. Pipes of smaller diameters generally do not become astightly wedged in the bending shoe cavities as do pipes of largerdiameters and accordingly, solid bending shoes properly lubricated witha graphite base or other suitable lubricant provide satisfactory releaseof small diameter pipes. The segmented bending shoe, as shown in FIGURE4, is comprised of a U-shaped outer casing 28 having upper and lowersurfaces 29 and 30, respectively, that diverge outwardly toward thebending face of the shoe. Contained within the outer casing 28 are upperand lower bending shoe segments 31 and 32, respectively, which areloosely secured to the casing by screws 33 comprising a threaded portion34 firmly attached to the bending shoe segments, an enlarged diametershank portion 35, and a round head 36. The length of the unthreadedshank 35 exceeds the thickness of the outer bending shoe casing betweenshoulders 37 of recess holes 38 and the back inner surface of, thecasing 28.

This arrangement enables each bending shoe segment to move forwardindependently out of the casing until heads 36 of screws 33 contactshoulders 37 of recess holes 33. Holes 39 in the casing through whichshanks 35 of screws 33 pass are enlarged, thereby permitting thesegments to move laterally as well as outwardly relative tothe casingbut small enough to prevent head 36 of screw 33 from passing through orbecoming wedged therein. During the forward bending stroke of the ramassembly the pipe 27 in the pipe'bending shoe cavity firmly seatsbending shoe segments 31 and 32 in the bending shoe casing 28. Oncompletion of the bend and retraction of the bending ram assembly thesegments 31 and and 32.

are able to withdraw partially from the casing to the extent permittedby screw shanks 35, enabling the segments to diverge outwardly alonginner surfaces 29 and 3% of the outer casing 28, opening thesemi-circular cavity in the bending shoes and thereby releasing the bentpipe.

A two-cavity segmented bending shoe is shown in FEG'URE 5 which issimilar in construction to the singlecavity shoe illustrated in FIGURE4. The two-cavity segmented shoe construction. has upper and lower sements 31 and 32, respectively, but requires, in addition, a middlesegment which is also movably connected to the outer casing 28, enablingits partial outward movement relative to the casing. ltwill beappreciated by those skilled in the art that multiple-cavity segmentedshoes of three or more cavities can be made based on the constructionillustrated in FIGURE 5. It is preferred that the segmented innerbending shoe dies be split along the horizontal length of thesemi-circular cavity therein in a plane passing through the approximatecenter of each cavity.

In the preferred embodiment of this machine, multiplecavity solidbending shoes are used for pipe diameters up to and including one andone-half inches. Solid bending shoes for three-quarter inch and one inchdiameter pipe have five cavities, shoes for one and one-quarter inchpipe have four cavities, while three cavities are employed in solidbending shoes for one and one-half inch diameter pipes. Segmentedbending shoes are used for bending pipes having diameters of one andone-half inches up to and including five inches.

' The drawing in FIGURE 7 represents an alternate method by which thebending shoes may be removably secured to the arcuate face of theoutermost ram extension die. This alternate method utilizes cap screw 41which is screwed into the back side of the pipe bending shoe 15 througha hole in the recessed rear center portion of the ram extension die. Twopins 24 projecting from the back surface of the bending shoe engage witha series of positioning holes 25 equally spaced along the face of theoutermost ram extension die. It will be noted that this alternate methodobviates the necessity of having grooves 21 in the upper and lowersurfaces of the ram exte ion dies 14 and bending shoe latching levers22. The pipe holding fixture is comprises of four radial link bars 4-2which are pivotally connected to the power unit housing 4 by means ofpins 43 and brackets 44 which are in vertical alignment. Each pair ofradial link rods 42 extends outwardly in parallel spaced-apartrelationship and disposed approximately 45 from the longitudinal centeraxis of the bending ram assembly 2 and hydraulic piston rod 12. Upperand lower cross link bars 45 are removably pinned to each pair of radiallink bars i2. by means of pins 46 which also provide the pivot supportfor. pipe holding shoes 4-7. The radial link bars 42 and. cross linkbars 45 have holes 43 equally spaced along the center line of theirrespective lengths, each of said holes having indiciaassociated'therewith such as a numbering or lettering sequence, wherebythe appropriate hole may be selected for mounting pipe holding shoes 47in accordance with the radius of the'bend to be made and diameter of thepipeto be bent. Pipe holding shoes 47 have a different set of cavitiesin each of their four faces corresponding to accesses.

5 the pipe holding cavities in the face of the pipe bending shoes 15.Two pair of pipe holding shoes 47 are required to provide the necessarysets of cavities to fit all the pipe sizes that can be bent in thismachine. The pipe holding shoes 47 are detachably secured to pins 46 bymeans of set screw 49 recessed in one face of the pipe holding shoe, asmay be best seen in FIGURE 8. The holding shoes are also provided with areturn spring mechanism whereby on completion of each bending cycle theholding shoes are returned to the starting position enabling theinsertion of the next length of pipe to be bent without requiring manualrepositioning of each holding shoe. Included in the holding shoe returnspring mechanism is a lever arm 50 adapted for sliding onto the upperend of a pin 46 and detachably secured thereto by set screw 51. AU-shaped clamp 52 slidably mounted on cross link bar 45 is linked tolever arm 50 by means of coil spring 53. A lug 54 extending downwardfrom the outer periphery of the base of the lever arm 50 provides a stopmechanism so that the pipe holding shoe will stop in the positiondesired. The clamp 52 is positioned along the upper cross link bar 45 sothat coil spring 53 is placed in tension while the lever arm 5'!) isheld in a rotatably fixed position by lug 54 in contact with the side ofthe upper cross link bar 45. In operation, the holding shoe 47 isrotated so that the holding shoe face having cavities corresponding tothe number and diameters of the pipes to be bent faces said cavities ofsaid shoe positioned in contach with said pipes which initially extendperpendicular to the longitudinal central axis of the bending ramassembly. In that position the lever arm 50 with lug 54 in contact withthe side of upper cross link bar 45 is locked to pin 46 by tighteningAllen set screw 51 and holding shoe 47 is also locked to pin 46 by setscrew 49. As the pipe is bent during the outward thrust of the bendingram assembly each of the holding shoes rotate inward toward the ram,causing pin 46 and lever arm 50 to rotate to the same degree, therebyincreasing the tension in coil spring 53. Upon removal of the bent pipefrom the holding shoe and bending shoe dies, the coil spring 53 actingthrough lever arm 56 rotatably retracts the bending shoes to theposition Where lug 54 is again in contact with the upper cross link bar.

A central guide track 56 disposed below and parallel with thereciprocating path of travel of the bending ram assembly 2, as may beseen in FIGURES l and 10, in conjunction with a roller carriage 57cooperating thereon provides a means for supporting and guiding thebending ram assembly during its reciprocating travel. Movable supportingspacers 58 elevate the central guide track 56 above the platform inorder that the lower cross link bar 45 may be adjusted withoutinterfering with the central guide track. The roller carriage '57, asshown in FIG- URES l and 11, is comprised of an inverted U-shapedchannel body 59 having rollers 60 rotatably mounted on shaft 61 rigidlysecured to opposing flanges 62 of the inverted U carriage body 59. Theside flanges 62 of the roller carriage are spaced apart a distanceslightly exceeding the width of the central guide track 56 and extenddown slightly below the upper surface of said guide track, therebycooperating intermittently with the side of said guide track stabilizingand guiding the carriage relative to the guide track which is secured bysuitable means or anchors to the base platform. A projection or pin 63extending from the front upper surface of the roller carriage 57 en ageswith holes 6 in the lower surface of the ram extension dies 14 removablyconnecting the carriage to the bending ram assembly. The use of theroller carriage 57 is preferred for all bending operations, although insituations where only a few ram extension dies 14 are used the weight ofthe bending ram assembly can be adequately supported by the hydraulicpiston rod 12. When large radius bends are being made requiring the useof a large number of ramextension dies 14, the weight of the bending ramassembly may cause unduly high stressesto be formed in the hydraulicpiston rod and piston assembly without the supporting help of the rollercarriage 57.

The automatic control mechanism for regulating the reciprocating travelof the bending ram assembly illustrated schematically in FIGURE 9 iscomprised of a slide bar 65 having a graduated upper surface and isrigidly supported in a horizontal position parallel to the longitudinalcenter axis of the hydraulic piston rod 12 and bending ram assembly 2 bymeans of clamp 66 securely attached to the forward outer periphery ofthe hydraulic piston rod 12. Supported from bracket 67 extendingoutwardly from the power unit housing 4 are limit switches 68 and 69which are actuated by cams 70 and 71 slidably mounted on slide bar 65.By the adjustment of cam 71 on slide bar 65 the forward travel of thebending ram assembly can be controlled by means of limit switch 69normally in an open contact position, which energizes servo motor 9 whenit becomes activated by cam 71. Upon being energized, electric servomotor 9 quickly rotates lower control lever 10 into the reverseposition, whereby the bending ram is quickly reversed. As the bendingram assembly is retracted cam 70 mounted on slide bar 65 approacheslimit switch 68 which is normally in a closed position but whenactivated by cam 7 0 opens, opening start relay contacts in starter box74, thereby deenergizing electric pump motor 5 and stopping the ram. Therapid reversal and instantaneous withdrawal of the bending ram assemblyprovided by this machine is essential in order to assure accurate bendswhich can be consecutively duplicated. The automatic shut-off orstopping action of limit switch 68 enables the ram to be stopped in aposition wherein the center pipe bending shoes are in transversealignment with the pipe holding shoes 47, allowing sufficient room sothat the next pipe or series of pipes to be bent can be inserted andheld between the holding shoes and bending shoes preparatory to the nextbending cycle.

It will be appreciated by those skilled in the art that alternate meansmay be employed to instantly reverse the forward thrust of the bendingram, such as an electric solenoid connected to a hydraulic slide valveslidable between forward, neutral, and reverse positions. The automaticcontrol feature of this bending machine makes the machine particularlysuitable for producing a large quantity of precision bent pipes whichmust be consecutively identical to each other. The extreme versatilityof this machine is further illustrated in FIGURES 12-16. The fragmentaryplan view of the pipe bending machine shown in FIGURE 12 illustrates theuse of the bending machine for imparting multiple bends in a length ofpipe, such as an offset, as shown in FIGURE 14. A pipe end stop 72 isgenerally employed to facilitate positioning the pipe lengthwiserelative to the bending ram. The configuration of pipe end stop 72 maybe of any general design enabling its removableattachment, as in FIG- URE 13, to the upper cross link bar 45 by means of pins 73.

A typical bending operation of the machine will now be described toprovide additional correlation between its operative parts. Assumingthat a one-inch diameter pipe is to be bent into an offset, as shown inFIGURE 14, the first step is to attach the appropriate number of ramextension dies 14 to the base ram 13 in accordance with the radius benddesired, and then the selected pipe bending shoes having five one-inchcavities in theirface are removably mounted on the arcuate outer face ofthe outermost ram extension die. Pipe holding shoes 47 are positioned inholes 48 by means of pins 46 corresponding to the radius of the bend anddiameter of the pipe to be bent. The holding shoe return springmechanisms are adjusted to correctly position the holding shoe faceshaving five one-inch cavities in transverse alignment with each other.The next step entails the adjustment of cams 70 and 71 on slide bar 65to set the reciprocating travel of the bending ram assembly so that, forexample, a 45 bend is achieved. Pipe end stop 72 is then positioned usome that the 45 bends will occur along the appropriate point of thepipes length. The bending ram assembly is then moved through onecomplete cycle in order that it stops at the appropriate point forinserting the pipe. Five oneinch diameter pipes are then insertedbetween the holdng shoes and pipe bending shoes with their ends abuttingpipe end stop '72. Lower control lever 16 is rotated into the forwardposition and electric pump motor is energized by a conventionalstart-stop push button switch which over-rides open limit switch 68 bymanually holding the starter relay in closed position until the rammoves outward to a point beyond which cam '70 on slide bar 65 no longeris in contact with limit switch 63, which then closes, holding thestarter relay in closed position until again activated by cam 70. Acomplete bending cyclethen ensues without requiring any furtherattention from the operator until the ram once again stops in theretracted position. The bent pipes are removed from the machine, turnedend for end, and reinserted as before and as shown in FIGURE 12. Leverit? is again pulled forward by the operator and pump motor 5 energized,thereby causing the machine to undergo another automatic bending cycle.The five pipes bent in an ofiset configuration, as shown in FIGURE 14,are then removed from the machine preparatory to the insertion of fiveadditional pipes to be subssquently bent.

In a similar manner, multiple bends, such as a saddle illustrated inFIGURE 15, can be accurately and quickly bent by this machine. Simplerbends, such as a 90 bend, or bends ranging from zero to slightly over90, such as a kick as shown in FIGURE 16, also can be bent quickly andconsecutively on this machine.

It will be understood that the invention herein described is not limitedto the exact details of construction and operation of the automaticmultiple radii pipe bending machine as shown in the drawings anddisclosed in the specification, inasmuch as various modifications can bemade by persons skilled in the art which are within the scope of theappended claims.

What is claimed is:

1. In a pipe bending machine, the combination comprising a frame, adouble acting fluid actuated cylinder on said frame having alongitudinally reciprocable piston rod, a variable radius bending rammounted on said rod and reciprocable thereby, said bending ramcomprising a base ram having an arcuate forward surface and a series ofarcuate tillers of progressively increasing radii detachably secured tosaid arcuate forward surface for varying the radius of said bending ram,and a plurality of pipe bending shoes arcuately disposed along theforward surface of the outermost of said arcuate fillers, each of saidbending shoes comprising a casing having an aligning pin in'the rearwardsurface thereof for slidably engaging a corresponding aligning bore inthe forward surface of the outermost of said arcuate fillers, aplurality of resiliently biased pivotally mounted latching levers onsaid casing for detachably engaging mounting grooves in the upper andlower surfaces of the outermost of said arcuate fillers, the forwardsurface of said casing formed to define a plurality of cavities ofsemi-circular cross-section for receiving and engaging piping of acorresponding diameter, said frame also having a pair ofradial-link barspivotally connected thereto and extending outwardly to each side of saidbending ram, a pair of cross-link bars extending transversely betweensaid link bars and detachably secured thereto by a pivot pin slidablyand rotatably disposed in aligned apertures through said radial and saidcross-link bars, a pair of holding shoes disposed between said pairs ofcross-link and radial-link bars and mounted on said pivot pins, each ofsaid holding shoes including a holding face formed to define cavities ofsemi:

circular cross-section corresponding to'said cavities in said bendingshoes, a lever detachably affixed to each of said pivot pins includingstop means thereon to'limit the rotational'travel of'each'ofsaid-holding-shoes in one direction to a start position in which saidholding face is perpendicular to the reciprocable path of travel of saidram, resilient means connected to each of said levers audto one ofsaidlink bars biasing said holding shoes toward said start position, guidemeans coacting with said bending ram disposed parallel to thereciprocable path of travel thereof, and presettable control means forcontrolling the forward and rearward travel of said bendmg ram.

2. In a pipe bending machine, the combination comprising a frame, adouble acting fluid actuated cylinder on said frame having alongitudinally reciproca ble piston rod, a variable radius bending rammounted on said rod and reciprocable thereby, said bending ramcomprising a base ram having an arcuate forward surface and a series ofarcust fillers of progressively increasing radii detachably secured tosaid arcuate forward surface for varying the radius of said bending ram,each of said arcuate fillers provided with a plurality of annularcollars at each of the ends thereof alignable with corresponding annularcollars on the ends of adjacent ones of said arcuate fillers forslidably receiving a securing pin for detachably securing said arcuatefillers together, and a plurality of pipe bending shoes arcuatelydisposed along the forward surface of the outermost of said arcuatefillers, each of said bending shoes comprising a casing having analigning pin in the rearward surface thereof for slidably engaging acorresponding aligning bore in the forward surface of the outermost ofsaid arcuate fillers, a plurality of resiliently biased pivotallymounted latching levers on said casing for detachably engaging mountinggrooves in the upper and lower surfaces of the outermost of said arcuatefillers, the forward surface of said casing formed to define a pluralityof cavities of semi-circular cross-section for receiving and engagingpiping of a corresponding diameter, said frame also having a pair ofradial-link bars pivotally connected thereto and extending outwardlytoeach side of said bending ram, a pair of cross-link bars extendingtransversely between said link bars and detachably secured thereto by apivot pin slidably and rotatably disposed in aligned apertures throughsaid radial and said cross-link bars, a pair of holding shoes disposedbetween said pairs of cross-link and radial-link bars and mounted onsaid pivot pins, each of said holding shoes including a holding faceformed to define cavities of semi-circular cross-section correspondingto said cavities in said bending shoes, a lever detachably atfixed toeach of said pivot pins including stop means thereon to limit therotational travel of each of said holding shoes in one direction to astart position in which said holding face is perpendicular to thereciprocable path of travel of said ram, resilient means connected toeach of said levers and to one of said link bars biasing said holdingshoes toward said start position, guide means coacting with'said bendingram disposed parallel to the reciprocable path of travel thereof, andpresettable control means for controlling the forward and rearwardtravel of said bending ram.

3. In a pipe bending machine, the combination com prising a frame, adouble acting fluid actuated cylinder on said frame having alongitudinally reciprocable piston rod, a variable radius bending rammounted on said rod and reciprocable thereby, said bending ramcomprising a base ram having an arcuate forward surface and a series ofarcuate fillers of progressively increasing radii detachably secured tosaid arcuate forward surface for varying the radius of said bending ram,and a plurality of pipe bending shoes arcuately disposed along theforward surface ofthe outermost of said arcuate fillers, each of saidbending shoes comprising an outer casing including a rearward wall andupper and lower diverging walls affixed thereto defining therewith aforwardly directed cavity, a segmented inner pipe bending die slida-blydisposed in said forwardly directed cavity and having aforward facedefining at least one cavity of a semhcircular cross-section, saidsegmented inner die segmented along the length of each of saidsemi-circular cavities in a plane passing through the approximate centerthereof, each of the segments of said segmented inner die being movablysecured to said rearward wall enabling the restricted outward movementthereof from said forwardly directed cavity, an aligning pin on theouter surface of said rearward wall for slidably engaging acorresponding aligning bore in the forward surface of the outermost ofsaid arcuate fillers, and securing means for detachably securing each ofsaid bending shoes to said outermost arcuate filler, said frame alsohaving a pair of radial-link bars pivotally connected thereto andextending outwardly to each side of said bending ram, a pair ofcross-link bars extending transversely between said link bars anddetachably secured thereto by a pivot pin slidably and rotatablydisposed in aligned apertures through said radial and said cross-linkbars, a pair of holding shoes disposed between said pairs of crosslinkand radial-link bars and mounted on said pivot pins, each of saidholding shoes including a plurality of holding faces formed to definecavities of semi-circular crosssection for receiving a variety ofdiiferent pipe sizes, a lever detachably affixed to each of said pivotpins including stop means thereon to limit the rotational travel of eachof said holding shoes in one direction to a start position in which anappropriate one of said holding faces is perpendicular to thereciprocable path of travel of said ram, and resilient means connectedto each of said levers and to one of said link bars biasing said holdingshoes toward said start position.

4. In a pipe bending machine, the combination comprising a frame, adouble acting fluid actuated cylinder on said frame having alongitudinally reciprocable piston rod, a variable radiusbending rammounted on said rod and reciprocable thereby, said bending ramcomprising a base ram having an arcuate forward surface and a series ofarcuate fillers of progressively increasing radii detachably secured tosaid arcuate forward surface for varying the radius of said bending ram,and a plurality of pipe bending shoes arcuately disposed along theforward surface of the outermost of said arcuate fillers, each of saidbending shoes comprising an outer casing including a rearward wall andupper and lower diverging walls afiixed thereto defining therewith aforwardly directed cavity, a segmented inner pipe bending die slidablydisposed in said forwardly directed cavity and having a forward facedefining at least one cavity of a semi-circular crosssection, saidsegmented inner die segmented along the length of each of saidsemi-circular cavities in a plane passing through the approximate centerthereof, each of the segments of said segmented inner die being movablysecured to said rearward wall enabling the restricted outward movementthereof from said forwardly directed cavity, an aligning pin on theouter surface of said rearward wall for slidably engaging acorresponding bore in the forward surface of the outermost of saidarcuate fillers, and securing means for detachably securing each of saidbending shoes to said outermost arcuate filler, said frame also having apair of radial-link bars pivotally connected thereto and extendingoutwardly to each side of said bending ram, a pair of cross-link barsextending transversely between said link bars and detachably securedthereto by a pivot pin slidably and rotatably disposed in alignedapertures through said radial and said cross-link bars, a pair ofholding shoes disposed between said pairs of cross-link and radial-linkbars and mounted on said pivot pins, each of said holding shoesincluding a plurality of holding faces formed to define cavities ofsemi-circular cross-section for receiving a variety of different pipesizes, a lever detachably affixed to each of said pivot pins includingstop means thereon to limit the rotational travel of each of saidholding shoes in one direction to a start position in which anappropriate one of said holding faces is perpendicular to thereciprocable path of travel of said ram, resilient means connected toeach of said levers and to one of said link bars biasing said holdingshoes toward said start position, a central guide track disposed belowand parallel to the reciprocating path of travel of said bending ram, aroller carriage contacting said guide track and removably attached tosaid bending ram for supporting and guiding said bending ram during thereciprocable travel thereof, and presettable control means forautomatically controlling the forward and rearward travel of saidbending ram.

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